Missed twins?

I went to the dr today for an early scan to confirm viability (recently had a missed miscarriage and DNC; I've had a total of 3 miscarriages now). We saw a heartbeat which is fantastic and I am measuring 8 weeks exactly. The sonographer however noticed some excess free fluid in my uterus and seemed concerned. She also asked if I had had <a href="https://glowing.com/glow-fertility-program">IVF</a> or if it was natural conception?! (It was natural conception). Just wondering if anyone has had the same and if it is possible there may be another one in there hiding OR any other explanation? Going to see the dr tomorrow for a follow up and really nervous. Thanks!